public class Test {
    
    public static void main(String[] args) {
        

        String a = "0";
        int b = 0;
        change(a);

        System.out.println(a);

        change(b);
        System.out.println(b);

        User u = new User("0");
        change(u);
        System.out.println(u.name);

    }


    private static void change(String data){

        data = "10";
    }

    private static void change(int data){

        data = 10;
    }

    private static void change(User data){

        data = new User("10");
    }

    private static class User{

        public User(String name){

            this.name = name;
        }

        public String name;

    }
}